1. Field of the Invention
The present invention relates to a sheet processing apparatus binding a received set of sheets, and in particular relates to a sheet processing apparatus used in conjunction with an image forming apparatus, such as a copying machine, a printer, etc.
2. Discussion of the Background
A sheet processing apparatus used in conjunction with an image forming apparatus, such as a copying machine, a printer, etc., receives sheets discharged from the image forming apparatus one after another, stacks and jogs the sheets, and performs processing, such as punching and/or binding, to the sheets.
In a system in which a sheet processing apparatus is connected with an image forming apparatus, it is known that when the speed of processing sheets of the sheet processing apparatus, such as jogging, punching and/or binding the sheets, is not comparable to the speed of forming images of the image forming apparatus, the image forming apparatus is controlled to stop forming images temporarily while the sheet processing apparatus is performing, for example, a binding operation.
It is also known to arrange a sheet waiting apparatus between a sheet processing apparatus and an image forming apparatus to avoid that the image forming apparatus is caused to temporarily stop forming images. Sheets discharged from the image forming apparatus one after another while the sheet processing apparatus is performing a binding operation to a previously received set of sheets are temporarily held at the sheet waiting apparatus, and the sheets are conveyed to the sheet processing apparatus after the binding operation to the previously received set of sheets has been completed at the sheet processing apparatus.
Further, in a system in which a sheet processing apparatus is connected with an image forming apparatus, when a malfunction has occurred at the sheet processing apparatus, the image forming apparatus is generally caused to stop operating. In this case, sheets remained in the sheet conveyance path of the image forming apparatus must be removed before restarting the sheet processing apparatus.
Furthermore, in such a sheet processing apparatus used in conjunction with an image forming apparatus, after a set of sheets has been bound, the bound set of sheets is discharged onto a discharge tray of the apparatus. In processing a plurality of sets of sheets one after another, the plurality of sets of sheets, each having been bound, are stacked on top of another on the discharge tray, so that when the bound set of sheets is thin, separating one from the other is relatively hard.